How to make a radio-distorted voice?

A sound design question eh?
 
You have already described what you need to do.
 
Sonar......A Parametric EQ shelved off correctly (Low and High) in the right spots or just search the sweet spots on Quad curve, some boost on the mid range and either a touch of gain or/and some distortion, TH2 would do the job with some Amp Simulation, also some tape emulation, some concrete limiter and a noise gate.

I do this effect all the time but no way will I reveal my sound design tricks on a public forum 

1-Sonar has FX-chains in its browser called Vox - Vocal Comb and Vox - Telephone Delay.  You can drag one of those into the FX bin and then play with the settings to get what you need.
2-EZ Mix also has a number of choices.  (Sorry, I don't remember which are in the standard set and which are in the Vocal Toolbox add-on).  These sound great.  "Crappy TV" and "Cosmonaut" are especially good.
 
From you description, I think you want an extreme midrange boost and an extreme cut of highs and lows.  You can clone the track, reverse phase on one track (which will effectively result in silence), and then on one track only, boost the midrange.  The result will be that you will have nothing except the boosted range.  You can move the boosted frequency around to find the sound you want.
 
For the static, you might look online for a radio static sound effect and add it on.  I download a lot of sound effects.  Some are free and some just cost a couple of dollars.
 
 

The main ingredient is high/low filer cuts.  As noted, there are various others things 'that can help - a hint of distortion.  A gate if you want a squelched sound (police, NASA, air traffic, military radios use this).  You can use phase to "lose" the signal.  Short delay to create ring.
 
Lots of fun.
 
@

The free iZotope Vinyl plugin will do it too:
http://www.izotope.com/products/audio/vinyl/
 

From memory bifilter 2.

mettelus

Silicon Audio
The free iZotope Vinyl plugin will do it too:
http://www.izotope.com/products/audio/vinyl/

Wow, that plug-in is something else... even runs with the transport stopped! I can see me putting this in a project and 2 years from now posting "Weird pops and crackles in only one project??" LOL

 
CW should insert this plugin under the hood and turn the date knob a decade or two clockwise with every new release, then they could claim a better sounding audio engine with every new version.

If you're using the iZotope Vinyl plugin, be sure to use the DirectX version, because otherwise the Warp Model and Warp Depth controls will be disabled. 

Buy a set of walkie talkies and record your best trucker talk. Over.

iamdunker
Buy a set of walkie talkies and record your best trucker talk. Over.

I'm reminded of that scene in The Young Ones where Nigel Planer is being instructed by Alexei Sayle in how to make a "kkkkkkhhhhh" sound for talking over a police radio.

The "Techniques" forum is probably more appropriate.
 
Here's what I would do though:

Shelve everything below about 800hz and everything above 8000hz.
 
Boost between 2000 and 6000hz to the point of clipping a tube emulator plugin--not completely overdriven, just enough to make it sound "hot" on transients and sibilance.
 
Add some white noise or static on another track and sidechain a gate using your vocal track to it so that it only keys when you're talking (in other words, you only hear the static when your voice track is producing sound).
 
You can add some short delay and amplitude modulation and play with phase if you want it to sound like the signal is dropping in and out (mentioned above).
 
These are all starting points, you'll have to kind of dial it in to get exactly what you want.
 
 

df12

AT
The main ingredient is high/low filer cuts.

What is a "filer cut"? I've searched the net and found nothing.

AT meant "filter," it was just a typo I'm sure.
 
Hi-pass and lo-pass filters.  AKA, shelving, or simply filters.
 
http://en.wikipedia.org/wiki/High-pass_filter
http://en.wikipedia.org/wiki/Low-pass_filter
 

Bad spelling and laziness catch up w/ me again.  Filter, no filer, even tho it is tax time here in the US.
 
@

Try an amp such as overloud. You could duck the amp with the vocal.